SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18672cade4e40819a6a213b79a163316fb69ffcbca7b3d8363b095d1e9d712ca' 
  AND token = 'Y9JGOMBTeclkM2bFQqz5VwSJn580RDihK6jVo/Y2OI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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