SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27efe1a0ca37b44d184b4ac70c72a626fa3e0e096865ab789de41d2978ed23f4' 
  AND token = 'wrURSlVw6SBpGnOLj8Eb9TuWh5lhegOG6KZuKlG+/3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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