SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d894b0844ebee8b87863f34d2bc83b4d66463099de50a298fe4b5ef988ac3df' 
  AND token = 'nb3pBPdJpIB0VSEkzUrsvw2ymUlROuvDxeujHGYNKXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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