SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '726baf043b25d685bcd9bc1f0130df38bc2af3467690ee85b84d5cd3e5d49d39' 
  AND token = 'VRAjQIP/LC9C8lWhUg6THjDCVgRpHiAXf6/QVCdwK2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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