SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66f8c7d9500744e40c89e7391556e1d93d1bd46f1243cd3146d2996d643c95e4' 
  AND token = '4rTCIqG0kbukRFo/1o0uarv5M8iYmiQw17ac7zuxvQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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