SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '527941f8f6966c6e280ee0b25834d2e3150835e31c84f1d0c352f0d7f583f8bb' 
  AND token = 't8e9l2VpkhXfqU8Q6rrrIAXHd5QJJkP7NhP3Ul5uIfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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