SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfc4b48d04363b1434071f6ce4a228346ec28d04626170c7492cecbd0e046a28' 
  AND token = 'h1B6JUBjvqKbDjOZ/w+e9pqhbwuQ4fmBfYgFLOHfoBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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