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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec3f1c2ccd9f1aca7a2e95e7bd6a7ea48607b715483c1b8258c8ca8dd0a75c3c' 
  AND token = 'q2YDsBFdBnEBq8vp4pOC5UuEWuQWNwJOU91DQ52tvb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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