SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11d755c7401c3615786d6223ce732dab0b43b416a00672cc352c868914af1df9' 
  AND token = 'Pt6hYzk2Hm/kZzGYPRWYqeWEeAvDEP4rExb+b47aD/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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