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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a37e7c2652fc737818735540ba0823a9b022438b8a2cb359d90d3c4473eb72' 
  AND token = 'UyuinISejEgj4cPt532Vnrc23CGbxPywsJXwrmIVsTI=' 
  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"
    }
  }
}