SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76083d010b1a43bd5d86ac27826b739271a8e3ce13a0204ff4bca53ed4371aff' 
  AND token = 'hKKK4gJ+feAP9pWUiPqKsTwQl9pRWKV/AVSbgC7fswc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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