SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92897621aa4cd78398dd2f36f662790a7008a3bee7e3c4ae5fbc3f0735c7494a' 
  AND token = 'BuSKiATzNoQTR8FkY6E/y+lQmojjxICkHFN9+hUsJZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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