SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40324b2f6340ca08cda0bf9348b0ddaf31da36801a452b3993d96f2f30525132' 
  AND token = 'cdST1uzQb9Aq8vl7vuIplABwu5m+pmhrzTMKCZlY+4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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