SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '719f43b2f09ccd18293bf4b6448900d3747e35967cd3c5aecb145f661070c4bc' 
  AND token = 'P8ZjvCCfeRd4iWaHZaThinKBjbKSlVOQVsWDWTfv62Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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