SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a6b563ddefca3634b883931422a9d28d9be14713bf32c1b713b3daeb86fe12' 
  AND token = 'mKIWj2aCsodCiCp62RZHP/uAqNhzrbVnICFY+W8MOAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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