SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83263b4cfbd32262602b6932fd50ade7a6340bc4204456d2bc3f3406fdc21999' 
  AND token = '0g6mRjj8TBmPbRqJbVZgiRq2XrWxzlwrGLEsJYJoISk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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