SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4909e91f708a91eb7cda9f3a7f520e24d611184450b88d325cfe35c8d2a46cdd' 
  AND token = '+ABwXtRxWqDnthJluOhjYqh6fhDpdOLH28/AazeA0m0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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