SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c356b389e0e71b2d44c4f64a96c17b1c7997cf8373182b120bdfbfa595f701ec' 
  AND token = '5vCyShekdWUOtshT96FH/asIJcBiBlk/PxunWUbxHLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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