SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6656e34c0c0496d65f0f5aa5319d1843ea813cecde72b82142b6a400a43e29df' 
  AND token = '51/IjGk8CLvPwQYhWXduPxs9ICs6weVpRF9BdWiNr+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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