SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7c9c81c20f87a760612694128626911f336023484dbf8c7e05f1d49c3399399' 
  AND token = 'XC8VZYBqoDpii5+ZKSitq7ZSsEMUjq9uc0GUb/2Z32w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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