SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f556dcac0206673040b112253485f3bad241ed24164da0a02ae90e97cb4b313' 
  AND token = 'Jr7aGr7apFQQ+JLdR18B54zKtd+f3TDJpV7ahGbQtmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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