SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba5b4cf7b5a9e4d0b5bc5bc7bde0cced2060af467d3318bc63774dc6cee95680' 
  AND token = 'mu1wqPZZnpvrDTHjFFYzmbEJqfch317aOyvh4a8d6mg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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