SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0db4b95446a0361ea1675a85995b2964c20efff8088fee48b0706d36bc6903f6' 
  AND token = '0eDsexJufaNvs833NBc5MniLqoqGd9n9gcgfOQpwc2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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