SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c9280fcb828d6bb7e873675f45645cc83beba0128971c8555859af9fca1896d' 
  AND token = 'P3wzijR9YzC7mHcY1uiFLuguC4lZvCqTS3DHG1Ng/z0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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