SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18818b0d198d05302967a41dd96c7cad85513a286327147128e8b0a6261d24ee' 
  AND token = 'vJMQvZxNyiRJgYBy36HfLXKkxIM+g6ox7NF0fc+dWlc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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