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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '502d2a8e55bb276fc279e4862cbcf4307d2685224f1c40d6d68d96861c27d1ad' 
  AND token = 'jeK3ceAUB+Q3UMR1OLm7AhRhfF87jOhQ59+pWOhz+Vo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}