SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3023225e87fb8dcf8127646145df7927897681280527516a963c2159273a63a' 
  AND token = 'bXUWaTAMbqv2RihwWQ+SFy7b3ukYuApJpsBEVdY4/CA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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