SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8addf7ae63adbec079478c74df9c994cc80259859497cee508386d6d86228ac3' 
  AND token = '0ZYLHWVG45QAIo9ncFdUmY9ShKkibg8ZhzA3vAvCmLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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