SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1d55ab9f2bd452cbd350e044e1778257a502438f6e4d23cb728f73c9310b5f8' 
  AND token = 'xPXxPWK4bepQlugwkAWQev8TkEZrqIN27vi+IH4njJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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