SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c8fc693f18dcfb028fcac5aeaa913aada9de0af91d818405df4d36b9c2f1e77' 
  AND token = 'EKpWFnNwmrC28fYvvBUc/snK5/f1ojo0tsBwwSeGVxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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