SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b199c5a911533b52b62b4085e2ed52978357ed3721cc1b3c4cd5682cf4deb31' 
  AND token = 'PYooVQmbyJz7NdOiRPWVt+q3hy2YQSfWVIWIKn+KJTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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