SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f737eb6d510d371f284e28a49fb55d40614a979b57cee481d6af4662c61affb' 
  AND token = 'roDOQbyLmyaPwXyQjFIMv8Qo3ZPFXuRLlepuvcw001A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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