SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c36e691db614ec422b878008e33f66e5acc39a7c905c439d233c2ff58424b47' 
  AND token = 'kxo2xlAKmtdlFPlyDZqCqphzXtA8+lQ+QIjMe/uQHL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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