SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2ca6aea414a873fb748ef436ae948aa2c341899b40ef3ce46ee6e6769c012c0' 
  AND token = '/+vtHghZHkWeLiGjcBOK6il3JF35kuqDUAD9rkNxDKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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