SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35abae6f9283cd0b165b5b303799f78864e5f27d7b14cf2a06e3b24a8ddb7419' 
  AND token = 'EECUd4fmh1+SaqWvAPjzbzGsYuJPsrUQQkDnjndz/J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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