SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e012d4adfdd77bf999b00274c2786a5eed7aeacb28e74fb778fc302a20cc3892' 
  AND token = 'm9RgL5ApYKCOekChctDlqFqVFZ9vLMK9ejbvQEyQyPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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