SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '842f31218d9c2422af3d1d9107667fd0de0d541c768fe7eec454dca5b42f0367' 
  AND token = 'iylrTq8PpXvhDSxG1x9+THV4UacYaET6tnkhuDnwr1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}