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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f900a67d2be264e1485cdc1a681f6068c48fd46300e4f9901e00b0f5a37dce14' 
  AND token = 'a7s+U786b2hGxXDRqzXcxmQURwRrFsDH8L1uFk9TDZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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