SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf5aeb1bba0dcd394f18b5c1a68c599077032d9645781ea552792d26301b3606' 
  AND token = 'kLUAZo4TKdNV+3ISn6BPO7nUaM191ZBTBoaYcC9py9I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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