SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '78edd7b9fa454a889cf83d66bf726ce9953aed85361d86f925072f41a52cda1b' 
  AND token = 'KCDQpElBOvRM+fv7sN0AbmrBSuwh70eHdfvmJpusXAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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