SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5eb67114530b9110498a737b8f45137314daa9abf8b80690701286b7f028f08' 
  AND token = 's9AdsigLhFzJZ7pHF608aYDUco6wt1etYjSLp5c0+QI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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