SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f61f2c2369f3bed6186b14b998442455d620a9876d6e75f32a4ad8fa9974230' 
  AND token = 'T/PblDRDxiYyrfc8QyG53d+iJ0qEwBAcIAhIioHn9n8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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