SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa975792e6df1f976888f0176dc2c1434caea492770334237ab9d60265ebc66a' 
  AND token = '7u4VIOyAPUn3uK28NaD/rYBK5qEiOozY5VWtsjoA3hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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