SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3da81a9642dfd348241567970174b235224b2b0ab7aa16f9910b10f4abedfe3' 
  AND token = 'rxdz73cLmSRA9J3oxmxiCvQyjXxW+FKs9qXuYiV+LT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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