SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3785997982baee1170f11ddad3bb6387c2934d79974f3b841b5e5b6a943c9d2' 
  AND token = 'JlMAbGt72Ug+QLmZjv7cuqj5hHf+kFElBP/ZpZX1eM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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