SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ffa19e2eb5858c8b755f9679f844b4da406ed49195b5b3303b45a9befdaef1b' 
  AND token = '5HgYHvGfRWCCIDwUQYeeZGu0DHg9tGwfxp5YTI4yA4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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