SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a39a61c701a404baeb36974c251ab336293fe00aaac498c34c2e73f01cfdc17' 
  AND token = 'qqJf/mhuBRhQ+NTRqDzD+wiImC9YLcvDjU7Bs+6isvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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