SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdaa4175051f579e992283c61ecc5c4690fbbe1f34d4db7e2e20714dc87c7b51' 
  AND token = 'lKKqcaPpzwXUGH0BVfKTvGjlMjNHOTDyaKNDpPeAYFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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