SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '131da326f547a44099362e3aa218139f40736cb7807689afe2ddff2b56c37fec' 
  AND token = 'dagjFjTXnq8bAQNrjljcFYgu/sWYmZpxpMIINd3Y2Nw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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