SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a447d570dd88a404fc5c5975ede25f1c6ec91fcffe0b5aa8938bda373d11f8ff' 
  AND token = 'eWRujF6mbRLa8JQyXY8lO8NXwT1hpdm0bWjKAvRJci8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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