SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f03b8928b2d629fa8794da72813ed46576cbd3deee6193cef0f4017e06f9fa3' 
  AND token = 'rcGoJhz/Ih2qmJutzY1TIl6Qwmxq472RLyvaATzLwCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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