SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd51fa34403235e90a099a4758ee2ad8510ab4cf75fd0524b07eaa1dc79a55094' 
  AND token = 'Zql4tY8x5BWy1gr7+gKk5U4pqdlnp4PRCKUZgvxAxYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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