SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a371d73de90a2092b214bd988cb409b834c51bbf296ff72b11ffbacde9c5bec7' 
  AND token = 'xLGvzd6wDWJxX+U+BOcpVxDZW+adtI2qlqaK1RWH8dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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