SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90508a89d81a5d47d7c20be4f7355281aa7479e39ad44a3c45685c5c093eff89' 
  AND token = 'XdxwXeI/1/4N9T5n0ZdPkjlSPW5w+EXWPdA+L+zILl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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