SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f345c9d87236b87b6106177199f81fe7c4862d4b5dbc78f1c68006491775f83d' 
  AND token = 'XFQ/L7AeGI1iwGHJvguRUJFw6iIyDXYp8qjfzVx7RzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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