SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83d0acdf630fa7b2394a12d6c9e2fcd2ad819da3e976969b4028b6cf991cc291' 
  AND token = 'bLsL5w5IcrAtG9lFrvXTqRYHJp/o/osSRTVorl61CVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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