SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd63baa9f5d95ed1bacba8813650827208c5d517d021d7b212de45a1dfae3c48' 
  AND token = 'PXCalsT31OizmtVgR7bmGE3NZ+GEuloxKOGcyXpdxHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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