SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9305822061df9814374ac950cbfc4bed229c30fcdc4e3b602018746f9340da3' 
  AND token = 'NQth3KjVyh4QANpSKmIzgvEu+8dI7QRRm8dFJzL7LHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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