SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8281040907ff25ceaec5d5756d09dc0c80d5be762077ccc5506bad1df3cf11bd' 
  AND token = '7OHKvMiYstUsbLEzw8+21mCdJFu7XUZDCZrIhD+0dwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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