SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa2aac7209ecffc5c17ad641de5f542a46b18c5b97494a2b2f06604e6842b131' 
  AND token = '1LTpIsEqoyk+cGbbiJ1gq+SEpPp7mlgOZviw4J50Gw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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