SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fd1e4d59a49a8df43cb97925d04541ebb4f71701762b4b744960f5965d7edc4' 
  AND token = '/cawvKSXOW9+ytOLjGRSqRmLW8wpcJaXBZP2DMqxLsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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