SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a5cdd6d37e1177d9b05fddf1c3d425ea81cb76f1f6dd4a85020c3896e83e8f1' 
  AND token = 'l1KitpsgZX4SSGRA9jTJIxSKU3bl27+uT2xphcWVhqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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