SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a7d31afa4784de64c2818f992df68178a5be6c4ebf312ea0ee1d6a52dbf14e4' 
  AND token = 'v9rwAyjXjH2j97uGsh5zInZ/6c/IPNV6XZC+Lh7nFfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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