SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4473ebe8f1405b35b59888bd324cb06fc917a4f3915cd1b0ddc20929a4b7ee7' 
  AND token = 'iOzjUAJDAiZkJSgB2AcvtO+1/ZVesvD0UhshYwmpIco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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