SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '792eee6e7094235447fc6873eb77afde2aa9bdd40f023436fc82a200f0921ac2' 
  AND token = 'l0GPNzod+FPdj4715GKDtslvSCABjZMqoVijNzsGgOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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