SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd17ad54d8a5827576bab6f121400a86577842ce14375412893087d6670ea86a2' 
  AND token = 'SJZ0tEMwepXRvBI8gksOSOgLgMokvYRln2dlQGFk2wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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