SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '388433837f645e2d3712dba389b8901ee26574239e0af793b207e996a971bfdd' 
  AND token = 'JHn9wqcLMRvY6CYAv8+fnYqwnuTfT9Vm4OuihcjYbDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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