SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac248fe7d87f88e165c0713e79d2d8a4c0f9a8974168c5cff9a5d2926d5f0e50' 
  AND token = 'p9qEF3pjnCfd3OIdSUDHqqp2iaSh/6F8Tzw5HMh1xk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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