SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81e071989fa613b1a2e698b636456be7bffc1ae65d106810a98c82a9257f0c84' 
  AND token = '5xBcxbiztRgjwhFOeaGf+Vg6u5SwGIGv4OEgOB4BUBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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