SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0636751430710d60e7b9650a19c115c86f7f749e2970e3cea406646424370579' 
  AND token = 'tTVTjo1qBN/L9kIdiv5rCmLN7BGi6exq+Bmz5GPJ8tI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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