SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c705387dbb85a6f9b3c06b6eddc14d449351b150917c3de53c8d0b7b624d12e' 
  AND token = 'kYZmUwPFpqevgFTV+kinB3phlhMjWV5BXSTK9/YSIzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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