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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b925c49f0a20119cca51c5df332ce87e3f7f0ab54815c46516f8f1f29f411984' 
  AND token = 'ZtUnFfsOS6K4S9jy/9afS98v3VPcJNMyscoqpltuqNc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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